1. Technical Field
The invention relates to vacuum cleaners. Particularly, the invention relates to a height adjustment mechanism for vacuum cleaners. Even more particularly, the invention relates to a height adjustment mechanism which includes a height adjustment cam formed with a ribbed camming surface for reducing the amount of force required to adjust the vacuum cleaner nozzle height.
2. Background Information
Because different types of carpets have different pile heights, conventional upright vacuum cleaners include variable height nozzles. A foot of these conventional uprights include some type of nozzle height adjustment mechanism which allows a user to adjust the height of the nozzle relative to a floor surface being cleaned.
Typically, these height adjustment mechanisms include a wheel carriage pivotally mounted to the foot of the upright vacuum cleaner. A height adjustment cam having a camming surface engages the wheel carriage and pivots the wheel carriage to raise or lower the height of the nozzle opening relative to the floor. The height adjustment cam is engaged by a cam actuator, such as a slide member, which is accessible from the outer surface of the foot. Such a height adjustment mechanism is shown and described in U.S. Pat. No. 5,134,750, assigned to a common assignee.
Although these prior art height adjustment mechanisms are adequate for the purpose for which they are intended, it is desirable to reduce the amount of force necessary to move the cam actuator to raise and lower the nozzle height. Such a reduction in force may be accomplished by reducing the surface-to-surface contact between the camming surface of the cam actuator and the wheel carriage. This reduced contact would reduce the amount of frictional resistance between the two members, thus requiring less force to operate the cam actuator.
Therefore, the need exists for a height adjustment mechanism which provides an easily operated cam actuator for raising and lowering the nozzle height relative to the floor surface.
Objectives of the invention include providing an improved height adjustment mechanism for a vacuum cleaner which reduces the amount of force required to operate the cam actuator as compared to prior art height adjustment mechanisms.
Another objective is to provide such a height adjustment mechanism which reduces the surface-to-surface contact between the height adjustment cam and the wheel carriage.
A further objective is to provide such a height adjustment mechanism which includes a plurality of predetermined nozzle heights.
A still further objective is to provide such a height adjustment mechanism which may be retrofit to existing upright vacuum cleaners
These and other objectives will be readily apparent from the following description taken in conjunction with the accompanying drawings.
In carrying out the invention in one form thereof, these objectives and advantages are obtained by providing an improved height adjustment mechanism for a vacuum cleaner, said vacuum cleaner including a foot formed with a nozzle opening, a height of said foot being adjustable relative to a surface being cleaned, said height adjustment mechanism including a wheel carriage which engages the surface and supports a front of the foot thereon, said wheel carriage being movable to adjust the height of the foot, a height adjustment cam movably mounted on the foot and having a camming surface for engaging the wheel carriage, and a cam actuator connected to the height adjustment cam for moving said height adjustment cam, the improvement comprising a plurality of longitudinally extending ribs formed on the camming surface for reducing the surface-to-surface contact between the height adjustment cam and the wheel carriage.